Stephen Posted July 17, 2023 Report Share Posted July 17, 2023 Aircraft Review : Rand Robinson KR-2S by NhAdrian As in the name X-Plane (Simulator), related to the series of X-Plane aircraft created by the Skunk Works, which is an official pseudonym for Lockheed Martin's Advanced Development Programs (ADP). In other words "Experimental", in design and in pushing the boundaries of flight. So X-Plane is based on that same simple philosophy. Not only can you fly odd, weird but strange designs, but you can create the same in Planemaker, as well as to checkout your theories in practice, or in the simulator. So it goes that the X-Plane Simulator is a very good basis for real world "Experimental" aircraft, in fact they thrive in this Simulation world in that you can relate to their very different types of flight dynamics. So here from NhAdrian is an interesting "Experimental" aircraft that can be built in "Kit form" from NVAero in Mission Viejo, California/Corona, California, United States. The original Rand Robinson KR-1 is a single-seat, single-engine sport aircraft designed in the United States in the early 1970s and marketed for homebuilding. The two-seat version is marketed as the KR-2, and is the same aircraft as reviewed here. This is also the 2S, which has a 16-inch-stretched-fuselage version of the KR-2, with 2.5 feet greater wingspan, made with composite sandwich construction, using the supercritical AS5045 airfoil. Standard engines choices include the 85 hp (63 kW) Jabiru 2200, 120 hp (89 kW) Jabiru 3300 and the 76 to 100 hp (57 to 75 kW) Volkswagen air-cooled engine. This particular aircraft uses the 2180 cc, at 80hp ((60kw) VW engine. The model also includes a 3-inch higher canopy and already 100 2S kit aircraft have been completed and flown by 2011. All aspects of this KR-2S are from a real world aircraft PH-KRS in dimensions, flight controls, instrumentation, flight dynamics and real world sounds. Modeling is very good, as it always is from NhArdian, but you can see the construction pieces as their whole, the single fuselage, created by a simple wood framework, with foam formers and an over fiberglass outer skin. The removable wings have twin built-up spruce spars and foam ribs, as do the empennage and control surfaces. So basically the construction is very similar in design to a model aircraft, just on a far larger scale. So it's a very, very clean design, with only the nose cowling as a separate section to access the engine... considering the design was originally of the 70's, it feels like a very modern design. Long smooth one piece wings, with a very nice uptake on the tip. inboard three stage flaps are tiny small, compared to the long main thin ailerons. The wing join mounts are highly visible, and easily not modeled, so that shows the attention to detail here, as are canopy catches. The KR is with it's controls that are are all cable activated. Push/pull in most cases, but give good control surface feedback. And those cable attachments can be seen popping out of the frame and wings in various places like for the rudder. Undercarriage is a very simple assembly, and every nut/bolt and brake assembly is created here, nice wear and tear as well. Notable is that the nose wheel is a simple loose castoring wheel, and a lot of these kit KR's are also taildraggers, but here it is the tri-cycle single wheel arrangement. There is a single taxi/landing light built into the nosewheel assembly, rough gear detail is very good and realistic. There is a huge forward bubble canopy, with a small window rear. Nice glass with reflections that highlight the roundness of the glass, all one piece it is well done. Your very aware that a single seater design has been widened to fit two people side by side, the cockpit is almost a rectangle head on, but the KR feels wide and squaty mid-fuselage Flip the canopy lever then raise it via lifting a protruding latch... ... two tight lay seats and a shelf space is set behind their heads. There are two deep pocket bins in the forward part of the shelf as well. Seats are basically pads or very slim cushions known as "conformal foam cushions" to fit in the cockpit, note the nice seatbelt webbing... Well done are the instruments, not at the front of the panel, but as seen from the rear as all the components and the wiring is fully on show. It is impressive work. You get the same under the panel as well, the full rudder pedal assembly, including the moving control cables, and note the huge fuel tank set before you to carry 12.6 USgal (48 Lts) of Avgas, the ideas are simplistic, but also very kit building in the detail. Instrument panel The "Panel" is the apt word here, as it's a single panel with all the few instruments and avionics set across it. There are four analog flight instruments... far left Airspeed, Altimeter, V/S Vertical Speed Indicator and upper mid-panel a Compass/Heading. There is also a "Winter" Slip Indicator below the EFIS. Dynon Avionics EFIS 10A Centre is a modern flight instrument in a Dynon Avionics EFIS-10A. This EFIS (Electric Flight Information System) is an innovative design that consolidates all your flight instruments into a sunlight-readable, 4" diagonal, color LCD. Six buttons below the LCD allow pilots to perform flight-related functions. There is a splash start-up screen when you turn the 10A on. The instrument provides; Attitude, Airspeed, Altitude, Turn-rate, Inclinometer, G-Meter, Up/Down Timers, Clock, and a Voltmeter. There are three options available via the buttons; Baro, Bugs and Timer Above the EFIS is a mounted iPhone or as noted "Navigational Phone". It is based on the AviTab (plugin required), with GPS information also supplied at each end of the screen. Avionics consist of four items; EIS (Engine Information System), Radio and Transponder, with a "Flightcom" 403 mc Panel Mount Intercom EIS covers; Engine RPM, Fuel volume in liter/10, Exhaust gas temperature (EGT), Oil temperature/pressure, Fuel pressure and Cylinder head temperature (CHT). The radio is based on the Funke KRT-2 and has the same LCD/button layout. Finally we have the Garrecht VT-01 and it has the same LCD/button layout as the same instrument. Circuit Breakers (Fuses) are all fully active, and work, and note the important central Electric Trim switch and display. Lower panel is the; Choke, Carburetor heat, Throttle, Fuel valve, Parking brake and Cabin heat. The flap handle is set between the seats in four stages, 0º (up) down to 38º. Passengers and Baggage There are two persons in the aircraft, a pilot (male) and a passenger (Female). If you adjust the X-Plane Menu "Weight, Balance & Fuel", to have above 50kgs on either the Pilot or Passenger then they will appear in the aircraft, both are also fully animated with movable heads and arms. Put the passenger weight below 50kgs and two bags will appear in the right seat. And if you select the Headphones connectors rear shelf, they put on a very nice set of headphones on to each person and dulls the overall sound. Finally selecting the seat bases will hide both people. There are no menus or external features (unless you count the AviTab as a feature), just the few hotspots for the Pilots, Audio, and the side air vents that when open can create more wind noise. __________________ Flying the Rand Robinson KR-2S You start the KR-2S like a car, because basically it is a car engine (Volkswagen), refitted into an aircraft fuselage, note there is even a "choke", I haven't used a choke for years with modern engine management systems and fuel injection. Switch up the secondary Ignition, turn on the fuel flow, and simply turn the key to start, and that familiar air-cooled VDub sound comes from the front of this actually very tiny aircraft. As headroom and knee room are just adequate for a six-footer. At 37 inches wide, the cockpit is very snug with two men in it, but full control throw is still easy on both of the short control columns, and the stick forces are light. Combined with those relatively big control surfaces and for the airframe’s ultra light weight. It sounds excellent, it should do as well as they all come the developers donor PH-KRS, and the feel aurally here is very, very good with FMOD2. So any adjustment of the throttle gives you the full range of VDub sounds, and in being positioned so close, it is, or can be quite loud. Let us get to the taxiing... it's well tricky. On the nose you have a castoring nosewheel, or a sort of reverse taildragger. There are two options in controlling it. Like a taildragger use your toe-brakes, but they are very, very sharp and twist you (quite violently) to either the right or left in their use, even with a soft touch, but you can make them work if you are very proficient in taildraggers. Secondly if you turn off the toe brakes the aircraft will revert to an X-Plane default were you steer with the yaw input. But that is compromised here as well, as the power of the thrust will allow the aircraft to turn (yaw) easily to the right, but harder to the left? If you gain a little speed, it will then turn to the left, but at a low turn speed (say onto a runway), then you have spin right around only to the right to go left on to runway. Yes it is all very authentic, it feels right, but makes the aircraft very difficult to taxi... there isn't even a wheel-lock to help in going straight with the toe-brakes.... tricky. One moment the KR will go left, then it won't so you circle right, then finally your facing the right way... its fun until it isn't. in v1.02, there has been added a "Steering Assistance" option. This is found on the X-Plane Menu KR-2S. Here you can switch to a yaw steering (either joystick or foot pedals) that helps the steering at lower speeds, but you lose the foot toe brakes, however the X-Plane (normal brakes) work fine. Don't get me wrong as the castoring nose wheel is very authentic to the KR-2S aircraft, it's built that way and works in the same way. Real pilots note that it is difficult to taxi cleanly.... it's home built after all. Oddly once you get onto the runway the KR-S2 will settle down and on power up to go quite straight, it has a lot of power for a small (but very light) aircraft and jumps off the line and moves sprightly forward. Surface aerodynamics kick in very, very quickly, so you soon have some effective rudder control. One thing you shouldn't do is to adjust the throttle, even a slight loss of power causes a "Power Drop", so keep it pulling forward. The very hard undercarriage has no give, so as the speed builds it can get a little blurry in the vision with the vibrations, then around 60 knts you feel the lift coming in and when pushing 70 kts you can rotate into a climb. So all your arms and legs are at work, controlling both the rudder and the stick, it's a busy aircraft to fly. Climb-out or Vertical Speed can be as high as 800 fpm, but your never going to use that with either another body or bags on board, but I will settle for 700 fpm... honestly the power from such a small 80hp (60kw) VDub engine is amazing, without it's heavy Beetle body, it just pulls, and pulls. Trim at takeoff is interesting as it totally depends on the weight... ... you can then have the odd situation of having a full down set trim or 5 notches down for takeoff, if the aircraft is set very heavy for it's size, it's a balance thing, as any weight reflects on the handling enormously... I was able to takeoff at a neutral trim setting, but I used a lot of runway to do so, but once in the air you fly up to you required altitude (1,500ft) then trim out to the lowest 5 number.... ... this were it gets interesting. As you have already used up all of your pitch trim, you then have to adjust or trim via the throttle to keep a consistent altitude, even then you need a slight pull (touch) in corrections to the stick. "Experimental" is the game here. Because you can (or need to) experiment on finding the best takeoff trim, then a level flight trim to suit your current conditions, either weight or weather... it's fun to adjust and find the right balance in the aircraft, not actually so much the trim, but the throttle position, and then you can find that level, even if it takes a few experimental flights to do so ... in this aspect the KR-S2 can feel very alive. It is all a very hands (and feet) on aircraft or "Stick and rudder", so light it can get very wriggly in the air, your trick is to find that smooth central point in it's balance and trim. You can find it, that cruise and negative pitch point, and just sail along, but you are still making constant corrections to the stick to keep the KR steady. Once you get it sorted, then your in a better place to turn the Rand around through the sky. The Aircraft is noted as "a lively, responsive, point-and-shoot airplane, with nice, crisp controls and a good, fighter-sharp roll rate, but not at all twitchy. Control forces were light in all three axes, and it needed a mere breath on the rudder to coordinate turns. Its handling was generally exemplary", and I agree with that aspect except that you can feel that small size o the controls and movement. A few years ago, one British couple did fly their KR-2 the 12,000 miles all the way from England to Australia, a truly impressive undertaking considering the "hands on" attitude I found with the aircraft and it's minute size. Performance is Cruise speed: 150–175 mph (241–282 km/h, 130–152 kn), Stall speed: 52–60 mph (84–97 km/h, 45–52 kn) with a Range: 1,300 mi (2,100 km, 1,100 nmi) with 35 U.S. gallons (130 L; 29 imp gal) of fuel, and a Service ceiling: 15,000 ft (4,600 m), the official Rate of climb is 800 ft/min (4.1 m/s). The aircraft is only suitable for VMC and day-VFR flights. Aerobatics are not allowed, but operating limitations mentioned among aerobatic maneuvers is only wing-overs, loops and rolls. Spins are recoverable and there are notes on how to do so, but a few pilot's have however died trying the spin manoeuvre. There is no lighting except for the single nose taxi/landing light, that includes the instruments. My first shot at landing didn't go very well at all... Dropping the flaps 38º had virtually no effect, and I continued to fly at 80 knts+, nose up to rub off the speed, and the KR-2S just floats or pitches slightly up with no loss of speed... actually gains height. So I abort the landing.... try that again. This time I knew I had to work harder, and earlier to contain the speed, as the KR does not react like a normal small GA aircraft. Once I get the speed below that 80 knt barrier I can find a speed and sink rate I like, and a sort of fall towards the runway. Throttle control is critical here, and at points almost full in, but I have better control of the approach... 70 knts! This time I think I have overplayed it too much the other way, once you slip past 60 knts you start to sink more, 55 knts is the landing speed, and I here went too slow... now going to low. Touch more throttle and I glide at the same 100 ft height, enough to get me to the hard stuff runway.... ... still flowing, then I let in more throttle and slip back to 55 knts in a slight flare and touch! The little KR will track and brake cleanly, until you again reach taxi speed. So again that word comes to mind... "experimental" and you need to experiment is with all the flight phases, takeoff, cruise and landing to find the right dynamics to suit the current weight and weather (wind) conditions, it is very addictive the Rand because of this so varied performance window. Finding the balance between throttle (power) and speed (even the right perfect pitch) for approaches takes experimenting, finding the yourself, and finding the aircraft, and it's curious behaviour. So for the "seat of the pants" pilot it is a great aircraft to test out their skills, maybe even learn a few more outside the usual flying envelope, the KR-2S weight and power is distinctly within the Sports Aircraft limitations, but it is a really interesting machine. Note, included in the manual is the full build history by Marcel Driessen of this KR-2S aircraft, including pictures and diagrams. It's a interesting story and on how long and how dedicated you have to be to build a ground up kit plane. __________________ KR-2S Liveries There are one blank and five liveries, Three Dutch and two American. This is a kit aircraft, so your not going to get a professional paint design, that said they are nice if basic designs. __________________ Summary "Experimental" aircraft are the foundation of the core of the X-Plane Simulator, it is a testing bed to try out designs, weird or not, but if they are sound in the way real world aerodynamics work. This aspect can transfer to Kit Aircraft, or home build aircraft like the one here from Rand Robinson, in the twin seater KR-2S, a small, very lightweight single car engined aircraft. The aircraft is a larger version of the original one seat KR-1, built in the 70's and now over the last 50 years has sold over 2,000 KRs that are still flying worldwide. This particular aircraft replicated here is a real aircraft PH-KRS, built by Marcel Driessen over ten years and now owned by the actual developer Adrián Nagy Hinst, so you do get a perfect replica of the Rand Robinson, in perfect detail, not only the actual aircraft in detail, but its real world (excellent) sounds and near perfect performance. It also delivers accurate engine and systems modelling, and fully operational circuit breaker system, accurate radio, transponder, Dynon EFIS and EIS instrument simulation including realistic screen content and functionality. And the aircraft is also fully VR (Virtual Reality) ready. It however does (as does the real aircraft) have a sort of taildragger loose wheel in reverse, or castoring nosewheel, that makes the aircraft difficult to steer on the ground, obviously a taildragger user will love it, but it is tricky to use, and even the developer has provided an artificial help via an menu option. Its oddly a deep simulation, because of the relationship to the real world aircraft, and you feel that through this excellent simulation, there are not a lot of options here or features, but that is not the point of the simulation. The point of the aircraft is to "experiment" with it, test your flying skills to match such a interesting aircraft in the way it fly's with very variable weight, balance and weather conditions, for the pilot jockey it is a great and interesting way to enjoy this sort of personal flying. So the Rand Robinson KR-2S goes deep into the X-Plane foundation of what at the core the X-Plane Simulator delivers, and yet yields a brilliant and interesting simulation in the process. ___________________________ Yes! - the Rand Robinson KR-2S by NHAdrian is NOW available from the X-Plane.Org Store here : Rand Robinson KR-2S Price is US$24.95 Requirements X-Plane 12 (not compatible with XP11) Windows. Mac or Linux 4 GB VRAM Minimum - 8 GB+ VRAM Recommended Download Size: 736 MB Current Version : 1.02 (July 19th 2023) Installation and documents: download for the Rand Robinson KR-2S is 702Mb and the aircraft is deposited in the "General Aviation" X-Plane folder. Full Installation is 814 MB AviTab Plugin is required. Document supplied is: KR2S_1.0.2 There is a huge amount of detail provided here, including installation, specifications, performance, instruments/avionics, but also X-Plane/hardware settings and Checklists. There is also an interesting story of the build of the donor PH-KRS by Marcel Driessen. Designed by NHAdrian Support forum for the KR-2S Review System Specifications Windows - 12th Gen IS1700 Core i7 12700K 12 Core 3.60 GHz CPU - 64bit -32 Gb single 1067 Mhz DDR4 2133 - PNY GeForce RTX 3080 10GB XLR8 - Samsung 970 EVO+ 2TB SSD Software: - Windows 11 Pro - X-Plane 12.05r1 (This is a Release Candidate review). Plugins: Traffic Global - JustFlight-Traffic (X-Plane.OrgStore) US$52.99 : Global SFD plugin US$30.00 : RK Apps XPRealistic v2 - US$34.99 Scenery or Aircraft - KHAF - Half Moon Bay Airport by Rising Dawn Studios (X-Plane.OrgStore) - US$19.90 ___________________________ Aircraft Review by Stephen Dutton 20th July 2023 Copyright©2023: X-Plane Reviews (Disclaimer. All images and text in this review are the work and property of X-PlaneReviews, no sharing or copy of the content is allowed without consent from the author as per copyright conditions) All Rights Reserved Kiwiflyer 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.